Portable computing devices such as laptop computers, netbooks, or tablet computers are typically constrained by their size or weight requirements and therefore provide a minimal number of connection ports (e.g. 1 or 2 USB ports and 1 display device port) for attaching peripheral devices. Therefore, it is common for users to supplement the number of built-in connection ports with an extension device such as a port replicator, a connection hub, or a docking station that provides additional connection ports. Similarly, extension devices are often used to maintain a predetermined configuration of connections to peripheral devices in order to eliminate the hassle of connecting and disconnecting peripheral devices individually. Accordingly, conventional extension devices are designed to provide an extended set of connections to typical peripheral devices and to provide a single or reduce set of corresponding connectors.
FIG. 1 depicts a conventional extension device 100. The extension device 100 provides a connection port 101 and a bus 102 for coupling a hub 103 to a computer. For example, bus 102 and connection port 101 may be a universal serial bus (USB) and a USB port, respectively. The hub 103 in turn connects the bus 102 to a plurality of peripheral devices 110 and 112.
The peripheral device 110 may be a device that requires a high-bandwidth connection with the computer. Accordingly, the extension device 100 may provide a high-bandwidth controller 120 for processing data transmitted over the high-bandwidth connection between the computer and the peripheral device 110. For example, if the high-bandwidth peripheral device 110 is a USB display device, the high-bandwidth controller 120 may be a digital graphical controller for processing the data transmitted between the computer and the USB display device.
Furthermore, the conventional extension device 100 typically requires an addressable controller 104 for maintaining the connection between the computer and the extension device 100.
Conventional extension device 100, however, exhibits several disadvantages. First, as the number of peripheral devices 110 and 112 attached to the hub 103 increases, the connection throughput to the computer may be degraded due to the competition between the peripheral devices 110 and 112. For example, since the hub 103 cannot prioritize or isolate the connection to the high-bandwidth device 110 from the connections to the one or more peripheral devices 112, the connection quality between the computer and the high-bandwidth device 110 is degraded when the number of peripheral devices 112 increases. Similarly, the connection quality to the high-bandwidth peripheral device 110 is degraded when the connection activity between the computer and the one or more peripheral devices 112 increases.
Second, the hub 103, by itself, degrades the quality of connections across it. For example, the hub may inherently introduce physical or electrical imperfections such as contact resistance or impedance, which degrade the connection quality across the hub. Also, the addressable controller 104 typically requires a software driver, which is installed on the computer and requires some connection bandwidth when it communicates with the computer. Thus, the hub 103 competes with the connection activities of the peripheral devices 110 and 112, thereby degrading the connection quality.
Accordingly, conventional extension devices are generally inadequate in maintaining a quality high-bandwidth connection with devices such as a display, a scanner, or a projector, etc. In the case of a display, the degradation causes dropped frames, for example. Furthermore, the conventional extension devices may require additional software configuration by the user, thereby adding unwanted complexity.